Export Formats supported by Audacity

Peter 11Dec14: The information contained in the bottom half of this page on the various file formats and the table for comparison of file sizes would be equally useful in the Export Multiple page. There all we say is "Export format: Choose one of the available export formats from this menu".

1. Rather than duplicate this material there (and we do always try to avoid duplication) I propose to spin that section off to a separate page with a title of something like "What format should I Export to?", "Export Formats supported by Audacity" or just "Export Formats".
2. This would also be useful in the Forum situation I encountered yet again yesterday where the user was enquiring about formats and I found myself directing him/her to an inadequate page in the Wiki.
3. It would also have the benefit of shortening this page for the reader who already knows what format they wish to export to.

• Gale 11Dec14: http://wiki.audacityteam.org/wiki/FileFormats is really only a landing page but at least the WAV, MP3 and OGG Wiki pages it links to have some useful content not necessarily neatly pulled together elsewhere. http://wiki.audacityteam.org/wiki/OGG looks too detailed to be in the Manual. As it is now we link from Manual to the Glossary for descriptions of formats.

  I don't object to a page in the Manual about Audacity-supported formats, but it creates a need for another click through versus leaving the information here. Perhaps you would like to make a draft page so we can see what it would contain? Note that the table below excludes formats mentioned in How can I export to formats not listed in the Export Audio Dialog? and excludes many of the "Other uncompressed" formats. How much detail do you want about all FFmpeg and other uncompressed formats? And what will you do about the WAV/AIFF/OGG and MP3 pages on Wiki?

• Peter 12Dec14: My main concern is occasioned by the fact that Export Multiple has absolutely no information on choice of format, apart from the fact that you can choose. Sure I could link from there to an anchor section on this page - but that then occasions a click from that page anyway so it may as well go to the new proposed page.

  ToDo-2 Yes I can start work on a draft page and will do so. Unsure yet about the level of detail but I will carry your comments over to that draft page and we can then work on it there in context.

  My feeling is that I would probably leave the WAV/AIFF/OGG and MP3 pages on the Wiki as there we can provide more detail if required, plus there may well be links to them - which probably means I'd also retain the Wiki parent page that links to them and probably upgrade it.

  Note too that Tutorial - Exporting to iTunes also has some material on choosing formats. Here it is limited, by design, to the smaller set of formats one is sensibly likely to use for iTunes/iPod usage. But is does have some material on why you'd choose compressed or uncompressed that may be valuable to include on the proposed now formats page.

  Which title would you prefer: "What format should I Export to?", "Export Formats supported by Audacity" or just "Export Formats"?

• • Other uncompressed files: includes all the uncompressed audio formats that Audacity can export, including 8-bit, 24-bit and 32-bit options. This menu item defaults to WAV (Microsoft) signed 16-bit PCM on Windows and Linux and to AIFF (Apple/SGI) signed 16 bit PCM on Mac.
  • AIFF (Apple/SGI) signed 16 bit PCM and WAV (Microsoft) signed 16 bit PCM: WAV and AIFF are uncompressed, lossless formats which can both be played on Windows or Mac computers. Choose WAV or AIFF 16-bit PCM whenever you want to burn your exported file to an audio CD.
  • GSM 6.10 WAV (mobile): produces a mono WAV file encoded with the compressed, lossy GSM 6.10 codec as used in mobile telephones.
  • MP3 Files: MP3 is a popular compressed, lossy format producing much smaller files than WAV or AIFF, at the expense of some loss of quality.
    You must download the optional LAME encoder to export to MP3.
  • OGG Vorbis Files: Ogg Vorbis is the compressed, lossy Vorbis codec in an OGG container. Vorbis offers higher quality than MP3 for the same file size, and is useful for good quality small-sized mono files, but fewer applications can play the OGG format.
  • FLAC Files: FLAC is a compressed but lossless format, giving larger file sizes than MP3 and OGG.
  • MP2 Files: MP2 is a compressed, lossy format similar to MP3, producing slightly larger files than MP3 for the same quality.
  • (external program): sends audio via the command-line to an external application either for processing or for encoding as a file. This is a method to export to an alternative MP3 encoder, or to a format not supported by Audacity.
  • FFmpeg formats: The following export types marked "(FFmpeg)" are listed in released builds of Audacity on Windows and Mac, and in other builds where FFmpeg is enabled. They will only function if you install the optional FFmpeg library.
    • M4A (AAC) Files: Advanced Audio Coding is a compressed, lossy format used in Apple applications, generally achieving slightly better quality than MP3 for the same file size. By default, the exported file will be given an "m4a" extension. Optional permitted extensions: .mp4, .m4r (ringtone) and .3gp (mobile).
    • AC3 Files: the common name used for the compressed, lossy format used in Dolby Digital.
    • AMR (narrow band) Files: the Adaptive Multi-Rate codec is a patented compression scheme optimized for speech, but also used for mobile telephone ringtones. The wide band variant uses higher bandwidth for higher quality.

AMR (wide band) export using 3GP extension (mono, 16000 Hz sample rate) may be made by choosing Custom FFmpeg Export (see below) if you obtain or compile a "shared" build of FFmpeg 1.2 or later that supports such encoding. The recommended FFmpeg library for Windows or Mac is suitable. Alternatively you can export AMR Wide Band using Audacity's command-line encoder pointing to a suitably built "ffmpeg" executable.
• WMA (version 2) Files: Windows Media Audio v2 is a compressed, lossy format developed by Microsoft. Optional permitted extensions: .asf or .wmv.
• Custom FFmpeg Export: Allows choice of the specific codec to use in the formats listed above, or to export to some additional formats not otherwise available. Note: not all formats and codecs are compatible, and some exports might result in zero-byte or invalid files if FFmpeg does not support the combination chosen.

File size and channel comparisons by export format

The following table gives typical achieved mono and stereo file sizes with different formats at default Audacity settings (that is, 44100 Hz sample rate and default bit rate or quality settings in the case of compressed formats). Where VBR compression is employed, the achieved size will vary depending on the content.

Some formats can be exported as multi-channel files containing more than two channels, if you enable this at "Use custom mix" in the Import / Export Preferences. The final column in the table shows the maximum number of channels per exported file.

Format	Lossy?	Compression	File size (MB per minute):		File size limit:	Channels
			mono	stereo
AC3	Yes	CBR	1.1	1.1		7
AIFF 16-bit PCM	No	None	5.0	10.0	4 GB(1)	32
AMR (NB)	Yes	CBR	0.1	-		1
FLAC 16-bit	No	VBR	2.5	5.0		8
GSM 6.10 WAV	Yes	CBR	0.5	-		1
M4A	Yes	VBR	-	1.1		32
MP2	Yes	CBR	1.1	1.1		2
MP3	Yes	CBR (optional VBR)	1.0 (CBR)	1.0 (CBR)		2
Ogg Vorbis	Yes	VBR	0.5	1.0		32
RF64 16-bit	No	CBR	5.0	10.0	~16 EB	32
WAV ADPCM (4-bit)	Yes	CBR	1.2	2.5	4 GB(1)	2
WAV A-Law/U-Law (8-bit)	Yes	CBR	2.5	5.0	4 GB(1)	32
WAV 16-bit PCM	No	None	5.0	10.0	4 GB(1)	32
WMA v2	Yes	CBR	1.3	1.3		2

(1)	The practical file size limit is 2 GB in many player applications due to their interpretation of the file size header. This also applies to 24-bit and 32-bit files where those bit depths are valid.